how do i mend my vauxhall mirvano 1.9 di engine?

my van has been faultless and this morning it stalled?
i have checked the fuel pump and filter all ok, the garage tells me the injectors have failed and is going to cost me a grand i think i am being ripped off as there as been no probs with power etc. i think it is something simple and they will fix and make good money... please can you help!